Thermal system with thermal pad filters

ABSTRACT

A thermal pad is adapted to be placed in physical contact with a patient and to receive temperature controlled fluid from a thermal control unit. The temperature controlled fluid circulates through the thermal pad and controls the patient&#39;s temperature. The thermal pad includes first and second sheets that are sealed together about their periphery to define a fluid chamber there between. A fluid inlet and fluid outlet are fluidly coupled to the fluid chamber. In some embodiments, a filter sheet is sandwiched between the first and second sheets and arranged such that fluid entering the fluid inlet must pass through the filter sheet before exiting out of the fluid outlet. A plurality of bonds may be included that seal the first and second sheets together at a plurality of locations. In some embodiments, a non-sheet filter is positioned within the fluid chamber and filters the circulating fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationSer. No. 62/778,034 filed Dec. 11, 2018, by inventors Andrew M. Bentz etal. and entitled THERMAL SYSTEM WITH THERMAL PAD FILTERS, the completedisclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a thermal control system forcontrolling the temperature of circulating fluid that is delivered toone or more thermal pads positioned in contact with a patient.

Thermal control systems are known in the art for controlling thetemperature of a patient by providing a thermal control unit thatsupplies temperature controlled fluid to one or more thermal padspositioned in contact with a patient. The thermal control unit includesone or more heat exchangers for controlling the temperature of the fluidand a pump that pumps the temperature controlled fluid to the pad(s).The pads are placed in contact with the patient and facilitate theexchange of thermal energy between the patient and the fluid circulatingthrough the pad, thereby either removing heat from the patient orsupplying heat to the patient. After passing through the pad(s), thefluid is returned to the thermal control unit where any necessaryadjustments to the temperature of the returning fluid are made beforebeing pumped back to the pad(s). The thermal control unit and itscoupled thermal pads can therefore be used to warm or cool a patient.

In one common arrangement, three pads are applied to the patient: oneapplied around the patient's torso, one applied around the patient'sright leg, and one applied around the patient's left leg. The pads areoften intended to be disposable such that, after use with a particularpatient, they are discarded.

SUMMARY

The present disclosure provides various improved aspects to a thermalcontrol system, including the thermal pads used with the thermal controlsystem. In some embodiments, one or more fluid filters are integratedinto the thermal pads to remove undesired matter from the fluid usedwith the thermal control system. The undesired matter includes, but itnot limited to, bacteria and other microorganisms. By including thefilters in disposable pads, fresh filters are automatically incorporatedinto the system whenever new thermal pads are used with the system(typically with every new patient), thereby allowing the thermal controlsystem to be continuously filtered and automatically supplied with freshfilters without requiring a user to manually change such filters. Otherimproved aspects of the thermal control system are also disclosed hereinand described in more detail below.

According to a first embodiment of the present disclosure, a thermal padis provided that is adapted to be placed in physical contact with apatient and to receive temperature controlled fluid from a thermalcontrol unit for controlling the patient's temperature. The thermal padincludes a first sheet, second sheet, peripheral seal, fluid inlet,fluid outlet, and a filter sheet. The first sheet is sheet adapted toface toward the patient and the second sheet is adapted to face awayfrom the patient. The peripheral seal couples a periphery of the firstsheet to a periphery of the second sheet to thereby define a fluidchamber between the first and second sheets. The fluid inlet and fluidoutlet are in fluid communication with the fluid chamber and providepassageways for delivering fluid to, and receiving fluid out of, thefluid chamber. The filter sheet has a first surface facing toward thefirst sheet and a second surface facing toward the second sheet. Thefilter sheet is positioned within the fluid chamber such that fluidentering the fluid inlet must pass through the filter sheet beforeexiting out of the fluid outlet.

According to other aspects of the embodiment, the filter sheet, firstsheet, and second sheet are all substantially parallel to each other.The filter sheet, second sheet, and first sheet all have a surface areaof substantially the same magnitude, in some embodiments.

According to another aspect, the thermal pad includes a plurality ofbonds wherein each of the bonds couples the first sheet, the secondsheet and the filter sheet together.

In other embodiments, the first sheet and second sheet each have asurface area of substantially the same magnitude and the filter sheethas a surface area of a magnitude less than the magnitude of the firstsheet and second sheet.

In at least one embodiment, the filter sheet is adapted to filterparticles having a size of 0.2 microns or larger. In some suchembodiments, a second filter sheet is also provided and is adapted tofilter particles larger than 0.2 microns and to allow particles of 0.2microns to pass therethrough.

In some embodiments, the first surface of the filter sheet is secured tothe first sheet at a first plurality of locations and the second surfaceof the filter sheet is secured to the second sheet at a second pluralityof locations that are different from the first plurality of locations.

A non-woven sheet positioned adjacent the first sheet and adapted tocome into contact with the patient is provided in some embodiments.Either or both of the non-woven sheet and the first sheet are embeddedwith antimicrobial substances.

In still other embodiments, the filter sheet itself includesantimicrobial substances embedded therein that are adapted to come intocontact with and kill microbes filtered by the filter sheet.

According to another embodiment of the present disclosure, a thermal padis provided that is adapted to be placed in physical contact with apatient and to receive temperature controlled fluid for controlling thepatient's temperature. The thermal pad includes a first sheet, secondsheet, peripheral seal, fluid inlet, fluid outlet, a plurality of bonds,and a filter. The first sheet is adapted to face toward the patient andthe second sheet is adapted to face away from the patient. Theperipheral seal couples the periphery of the first sheet to a peripheryof the second sheet to thereby define a fluid chamber between the firstand second sheets. The fluid inlet and fluid outlet are in fluidcommunication with the fluid chamber and provide passageways fordelivering fluid to, and receiving fluid out of, the fluid chamber. Theplurality of bonds couple the first sheet, second sheet and filter sheettogether. The filter is secured to the first sheet and the second sheet,and is positioned within the fluid chamber such that fluid entering thefluid inlet must pass through the filter sheet before exiting out of thefluid outlet.

According to other aspects, the thermal pad may also include a secondfilter and a third filter. When included, the second filter ispositioned upstream of the filter and adapted to filter particles havinga size of more than 0.2 microns and to allow particles of 0.2 microns topass therethrough. The third filter is positioned downstream of thefilter and adapted to filter particles having a size of more than 0.2microns and to allow particles of 0.2 microns to pass therethrough.

In some embodiments, the filter defines a fluid channel that extendsinto the thermal pad. The channel may extend a distance into the thermalpad that is at least half of a length of the thermal pad or at leasthalf of a width of the thermal pad. The filter may be bag shaped with aninterior of the bag defining the fluid channel. In some embodiments, thebag shaped filter includes a top filter sheet and a bottom filter sheetand the plurality of bonds also bond the top filter sheet and the bottomfilter sheet to each other and to the first sheet and second sheet.

According to another embodiment, a thermal pad is provided that isadapted to be placed in physical contact with a patient and to receivetemperature controlled fluid from a thermal control unit for controllingthe patient's temperature. The thermal pad includes a first sheet,second sheet, peripheral seal, fluid inlet, fluid outlet, and first,second, and third filters. The first sheet is sheet adapted to facetoward the patient and the second sheet is adapted to face away from thepatient. The peripheral seal couples a periphery of the first sheet to aperiphery of the second sheet to thereby define a fluid chamber betweenthe first and second sheets. The fluid inlet and fluid outlet are influid communication with the fluid chamber and provide passageways fordelivering fluid to, and receiving fluid out of, the fluid chamber. Thefirst, second, and third filters are all positioned in fluidcommunication with the fluid chamber. The third filter is alsopositioned between the first and second filters such that fluid flowingthrough the first filter must pass through the third filter beforereaching the second filter. The first and second filters have a commonpore rating for filtering particles of a first size, and the thirdfilter has a pore rating for filtering particles of a second size. Thesecond size is smaller than the first size.

According to other aspects of this embodiment, the third filter may havea pore rating for filtering particles having a size of 0.2 microns orlarger and the first and second filters may have a pore rating forallowing particles having a size of greater than 0.2 microns to passtherethrough.

A non-woven sheet is provided in some embodiments that is positionedadjacent the first sheet and adapted to come into contact with thepatient. The non-woven sheet is embedded with antimicrobial substances.

The third filter, in some embodiments, is a filter sheet comprising afirst surface facing toward the first sheet and a second surface facingtoward the second sheet. The filter sheet, first sheet, and second sheetare all substantially parallel to each other.

The first filter and the second filter, in some embodiments, definefirst and second channels that extend a distance into the thermal pad.The first filter and second filter may both be bag shaped, and theinterior of the bag shaped filters defines the first and secondchannels, respectively.

According to another embodiment of the present disclosure, a thermal padis provided that is adapted to be placed in physical contact with apatient and to receive temperature controlled fluid from a thermalcontrol unit for controlling the patient's temperature. The thermal padincludes a first sheet, second sheet, peripheral seal, fluid inlet,fluid outlet, first connector, second connector, an inlet hose segment,an outlet hose segment, and a filter. The first sheet is sheet adaptedto face toward the patient and the second sheet is adapted to face awayfrom the patient. The peripheral seal couples a periphery of the firstsheet to a periphery of the second sheet to thereby define a fluidchamber between the first and second sheets. The fluid inlet and fluidoutlet are in fluid communication with the fluid chamber and providepassageways for delivering fluid to, and receiving fluid out of, thefluid chamber. The first connector is adapted to releasably couple to asupply hose from a thermal control unit. The second connector is adaptedto releasably couple to a return hose of the thermal control unit. Theinlet hose segment includes a first end coupled to the first connectorand a second end coupled to the fluid inlet. The outlet hose segmentincludes a first end coupled to the second connector and a second endcoupled to the fluid outlet. The filter is positioned inside of at leastone of the inlet hose segment and the outlet hose segment such thattemperature controlled fluid supplied from the thermal control unit isfiltered as it passes through the filter pad.

According to other embodiments, the filter pad includes a second filter.In such embodiments, the filter is positioned in the inlet hose segmentand the second filter is positioned in the outlet hose segment. In someembodiments, a third filter is positioned within the fluid chamber. Thethird filter may have a different pore rating than the filter and thesecond filter. The third filter may be a filter sheet coupled to thefirst and second sheets by a plurality of bonds.

Before the various embodiments disclosed herein are explained in detail,it is to be understood that the claims are not to be limited to thedetails of operation or to the details of construction, nor to thearrangement of the components set forth in the following description orillustrated in the drawings. The embodiments described herein arecapable of being practiced or being carried out in alternative ways notexpressly disclosed herein. Also, it is to be understood that thephraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the claims to any specific order or number of components. Norshould the use of enumeration be construed as excluding from the scopeof the claims any additional steps or components that might be combinedwith or into the enumerated steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a thermal control system according toone aspect of the present disclosure shown applied to a patient on apatient support apparatus;

FIG. 2 is a block diagram of the thermal control system of FIG. 1showing further internal details of one example of a thermal controlunit usable with the thermal control system of FIG. 1 ;

FIG. 3 is another block diagram of the thermal control system of FIG. 1showing further details of the hose constructions of a first set ofthermal pads that are usable with the thermal control system;

FIG. 4 is an exploded view of one of the thermal pads of FIG. 3 ;

FIG. 5 is a plan view of a first alternative embodiment of a thermal padusable with the thermal control system of FIG. 1 ;

FIG. 6 is a sectional view of the thermal pad of FIG. 5 taken along theline VI-VI in FIG. 5 ;

FIG. 7 is a modified version of the thermal pad embodiment of FIGS. 5-6;

FIG. 8 is a second alternative embodiment of a thermal pad usable withthe thermal control system of FIG. 1 ;

FIG. 9 is a sectional view of the thermal pad of FIG. 8 taken along theIX-IX in FIG. 8 ;

FIG. 10 is a sectional view of the thermal pad of FIG. 8 taken along theline X-X in FIG. 8 ;

FIG. 11 is a plan view of a third alternative embodiment of a thermalpad usable with the thermal control system of FIG. 1 ;

FIG. 12 is a sectional view of the thermal pad of FIG. 11 taken alongthe line XII-XII in FIG. 11 ;

FIG. 13 is a sectional view of the thermal pad of FIG. 11 taken alongthe line XIII-XIII in FIG. 11 ,

FIG. 14 is a plan view of a fourth alternative embodiment of a thermalpad usable with the thermal control system of FIG. 1 ;

FIG. 15 is a sectional view of the thermal pad of FIG. 14 taken alongthe line XV-XV in FIG. 15 ;

FIG. 16 is a sectional view of the thermal pad of FIG. 14 taken alongthe line XVI-XVI in FIG. 15 ;

FIG. 17 is a plan view of a fifth alternative embodiment of a thermalpad usable with the thermal control system of FIG. 1 ;

FIG. 18 is a sectional view of the thermal pad of FIG. 17 taken alongthe line XVIII-XVIII in FIG. 17 ;

FIG. 19 is an exploded, partial perspective view of the thermal pad ofFIG. 17 ; and

FIG. 20 is a sectional view of a sixth alternative embodiment of athermal pad usable with the thermal control system of FIG. 1 .

DETAILED DESCRIPTION OF THE EMBODIMENTS

A thermal control system 20 according to one embodiment of the presentdisclosure is shown in FIG. 1 . Thermal control system 20 is adapted tocontrol the temperature of a patient 30. Such temperature control mayinvolve raising, lowering, or maintaining the patient's temperature, orcombinations thereof. Thermal control system 20 includes a thermalcontrol unit 22 coupled to one or more thermal therapy devices 24. Thethermal therapy devices 24 are illustrated in FIG. 1 to be thermal pads,but it will be understood that thermal therapy devices 24 may take onother forms, such as, but not limited to, blankets, vests, patches,caps, or other structure. For purposes of the following writtendescription, thermal therapy devices 24 will be referred to as thermalpads 24, but it will be understood by those skilled in the art that thisterminology is used merely for convenience and that the phrase “thermalpad” is intended to cover all of the different variations of thermaltherapy devices 24 mentioned above (e.g. blankets, vests, patches, caps,etc.).

Thermal control unit 22 is coupled to thermal pads 24 via a plurality ofhoses 26. Each thermal pad 24 includes a supply hose 26 a and a returnhose 26 b. Thermal control unit 22 delivers temperature controlled fluid(such as, but not limited to, water) to the thermal pads 24 via thefluid supply hoses 26 a. After the temperature controlled fluid haspassed through thermal pads 24, thermal control unit 22 receives thetemperature controlled fluid back from thermal pads 24 via the returnhose 26 b. In some modified embodiments of thermal control system 20,one or more auxiliary lines may be coupled between the thermal controlunit 22 and one or more of the thermal pads. Such auxiliary lines mayprovide thermal control unit 22 with additional data regarding thepatient, the thermal pads 24, and/or other information, or suchauxiliary lines may provide a conduit for supplying a different fluid(e.g. a gas) to the thermal pads. Still other purposes may be served bythe auxiliary line. Examples of the types of auxiliary lines that may beused in such modified thermal control systems are disclosed in thefollowing commonly assigned U.S. patent applications: Ser. No.15/675,061 filed Aug. 11, 2017, by inventors James K. Galer et al., andentitled THERMAL THERAPY DEVICES; Ser. No. 15/820,558 filed Nov. 22,2017, by inventors Gregory S. Taylor et al. and entitled THERMAL SYSTEM;and Ser. No. 62/610,327 filed Dec. 26, 2017, by inventors Gregory S.Taylor et al. and entitled THERMAL SYSTEM WITH PATIENT SENSOR(S), thecomplete disclosures of all of which are incorporated herein in theirentirety by reference. Still other types of auxiliary lines may becoupled between thermal control unit 22 and thermal pads 24.

In the embodiment of thermal control system 20 shown in FIG. 1 , threethermal pads 24 are used in the treatment of patient 30. A first thermalpad 24 is wrapped around a patient's torso, while second and thirdthermal pads 24 are wrapped, respectively, around the patient's rightand left legs. Other configurations can be used and different numbers ofthermal pads 24 may be used with thermal control unit 22, depending uponthe number of inlet and outlet ports that are included with thermalcontrol unit 22. By controlling the temperature of the fluid deliveredto thermal pads 24 via supply hoses 26 a, the temperature of the patient30 can be controlled via the close contact of the pads 24 with thepatient 30 and the resultant heat transfer therebetween.

In some embodiments, such as that shown in FIG. 1 , one or more of thehoses 26 may be partially or wholly enveloped in a thermal covering 28in order to help prevent heat transfer between the fluid inside thehoses 26 and the surrounding ambient air. The thermal covering 28 may bemade from any suitably flexible material having good thermal resistance.

Thermal control unit 22 is adapted to raise or lower the temperature ofthe fluid supplied to thermal pads 24 via supply hoses 26 a. As shown inFIG. 2 , thermal control unit 22 includes a pump 32 for circulatingfluid through a circulation channel 34. Pump 32, when activated,circulates the fluid through circulation channel 34 in the direction ofarrows 36 (clockwise in FIG. 2 ). Starting at pump 32 the circulatingfluid first passes through a heat exchanger 38 where it is delivered toan outlet manifold 40 having an outlet temperature sensor 42 and aplurality of outlet ports 44. Outlet ports 44 are adapted to fluidlycouple to supply and return hoses 26 a and 26 b. In some embodiments, aplurality of valves (not shown) may also be included within outletmanifold 40 in order to individually control the amount of fluid exitingthose ports 44 that are coupled to supply hoses 26 a, thereby allowingthe thermal control unit 22 to individually control how much fluid flowsto each of the pads 24. In other embodiments, such valves are omitted.Although FIG. 2 illustrates three outlet ports 44, it will be understoodthat this number may vary.

Temperature sensor 42 is adapted to detect a temperature of the fluidinside of outlet manifold 40 and report it to a controller 46. As willbe discussed more below, controller 46 uses this temperature reading asfeedback for the control of heat exchanger 38. Thermal control unit 22also includes a bypass line 48 fluidly coupled to outlet manifold 40 andan inlet manifold 50. Bypass line 48 allows fluid to circulate throughcirculation channel 34 in a complete circuit even in the absence of anythermal pads 24 or hoses 26 a being coupled to any of outlet ports 44.That is, bypass line 48 allows fluid to flow from heat exchanger 38 toinlet manifold 50. From inlet manifold 50, the fluid is able to flowback to pump 32, which is fluidly coupled thereto by circulation channel34. The fluid is therefore able to make a complete circuit withinthermal control unit 22. In some embodiments, bypass line 48 includes avalve used to control when and how much fluid is allowed to flow throughbypass line 48. The valve, if included, may be a pressure operated valvethat responds to the fluid pressure, or it may be a valve controlled bycontroller 46.

Inlet manifold 50 includes a plurality of inlet ports 52 (the precisenumber may vary from the three illustrated in FIG. 2 ) that couple toreturn hoses 26 b and receive fluid returning from the one or moreconnected thermal pads 24. The incoming fluid from inlet ports 52, aswell as the fluid passing through bypass line 48, travels back towardthe pump 32 into an air separator 54. Air separator 54 includes anystructure in which the flow of fluid slows down sufficiently to allowair bubbles contained within the circulating fluid to float upwardly andescape to the ambient surrounding. In some embodiments, air separator 54is constructed in accordance with any of the configurations disclosed incommonly assigned U.S. patent application Ser. No. 15/646,847 filed Jul.11, 2017, by inventor Gregory S. Taylor and entitled THERMAL CONTROLSYSTEM, the complete disclosure of which is hereby incorporated hereinby reference. After passing through air separator 54, the circulatingfluid flows past a valve 56 positioned beneath a fluid reservoir 58 thatsupplies fluid to thermal control unit 22. After passing by valve 56,the circulating fluid travels to pump 32 and the circuit is repeated.

Controller 46 of thermal control unit 22 is contained within a main bodyof thermal control unit 22 and is in electrical communication with avariety of different sensors and/or actuators. More specifically,controller 46 is in electrical communication with pump 32, heatexchanger 38, outlet temperature sensor 42, and a control panel 60(FIGS. 1 & 2 ). Control panel 60 includes a plurality of controls 62that allow a user to operate thermal control unit 22, including settinga desired fluid target temperature and/or a desired patient targettemperature, and/or to control other aspects of thermal control unit 22.Control panel 60 communicates with controller 46 and includes controlsenabling a user to turn control unit 22 on and off, as well as one ormore controls enabling the user to select a target temperature for thefluid delivered to thermal pads 24. In some embodiments, control panel60 also allows a user to select from different modes for controlling thepatient's temperature. One of the modes includes a manual mode in whichthe user selects a target temperature for the fluid. Control unit 22then makes adjustments to heat exchanger 38 in order to ensure that thetemperature of the fluid exiting supply hoses 26 a is at theuser-selected temperature.

Another one of the modes is an automatic mode. When the user selects theautomatic mode, the user selects a target patient temperature, ratherthan a target fluid temperature. After selecting the target patienttemperature, controller 46 makes automatic adjustments to thetemperature of the fluid in order to bring the patient's temperature tothe desired patient target temperature. In this mode, the temperature ofthe circulating fluid may vary as necessary in order to bring about thetarget patient temperature. Both the manual and automatic modes can beused for cooling and heating the patient.

In some embodiments, when the user selects the automatic mode, thethermal control unit 22 is configured to allow the user to select one ormore desired heating or cooling rates for use in the automatic mode.When such rates are selected by the user, thermal control unit 22 notonly brings the patient to the target patient temperature, but does soat the rate specified by the user. Still other variables, such as themaximum difference between the patient's temperature and the fluidtemperature, may also be selected by the user using control panel 60, inat least some embodiments.

Control panel 60 may take on a wide variety of different forms. In someembodiments, control panel 60 may include any of the features andfunctionality of the control panel 46 disclosed in commonly assignedU.S. patent application Ser. No. 14/282,383 filed May 20, 2014, byinventors Christopher J. Hopper et al. and entitled THERMAL CONTROLSYSTEM, the complete disclosure of which is incorporated herein byreference. Additionally, or alternatively, control panel 60 may includeany of the features and/or functionality of the user interface 76 and/ordisplay 80 disclosed in commonly assigned U.S. patent application Ser.No. 62/610,362 filed Dec. 26, 2017, by inventor Gregory S. Taylor andentitled THERMAL SYSTEM WITH GRAPHICAL USER INTERFACE, the completedisclosure of which is also incorporated herein by reference. Stillfurther, control panel 60 may include one or more controls 62 forimplementing a pause/event control, a medication control, and/or anautomatic temperature adjustment control, wherein these controls operatein accordance with the pause event control 66 b, medication control 66c, and automatic temperature adjustment control 66 d disclosed incommonly assigned U.S. patent application Ser. No. 62/577,772 filed onOct. 27, 2017, by inventors Gregory Taylor et al. and entitled THERMALSYSTEM WITH MEDICATION INTERACTION, the complete disclosure of which isalso incorporated herein by reference. Such controls may be activated astouch screen controls or dedicated controls.

Controller 46 includes any and all electrical circuitry and componentsnecessary to carry out the functions and algorithms described herein, aswould be known to one of ordinary skill in the art. Generally speaking,controller 46 may include one or more microcontrollers, microprocessors,and/or other programmable electronics that are programmed to carry outthe functions described herein. It will be understood that controller 46may also include other electronic components that are programmed tocarry out the functions described herein, or that support themicrocontrollers, microprocessors, and/or other electronics. The otherelectronic components include, but are not limited to, one or more fieldprogrammable gate arrays, systems on a chip, volatile or nonvolatilememory, discrete circuitry, integrated circuits, application specificintegrated circuits (ASICs) and/or other hardware, software, orfirmware, as would be known to one of ordinary skill in the art. Suchcomponents can be physically configured in any suitable manner, such asby mounting them to one or more circuit boards, or arranging them inother manners, whether combined into a single unit or distributed acrossmultiple units. Such components may be physically distributed indifferent positions in thermal control unit 22, or they may reside in acommon location within thermal control unit 22. When physicallydistributed, the components may communicate using any suitable serial orparallel communication protocol, such as, but not limited to, CAN, LIN,Firewire, I-squared-C, RS-232, RS-485, universal serial bus (USB), etc.

When operating in the automatic mode, thermal control unit 22 utilizes apatient temperature module 64 (FIG. 2 ). Patient temperature module 64includes one or more patient temperature sensor ports 66 that areadapted to receive one or more conventional patient temperature sensorsor probes 68. The patient temperature probes 68 may be any suitablepatient temperature sensor that is able to sense the temperature of thepatient at the location of the sensor. In one embodiment, the patienttemperature sensors are conventional Y.S.I. 400 probes marketed by YSIIncorporated of Yellow Springs, Ohio, or probes that are YSI 400compliant. In other embodiments, different types of sensors may be usedwith thermal control unit 22. Regardless of the specific type of patienttemperature sensor used in thermal control system 20, each temperatureprobe 68 is connected to a patient temperature sensor port 66 positionedon thermal control unit 22. Patient temperature sensor ports 66 are inelectrical communication with controller 46 and provide currenttemperature readings of the patient's temperature.

Controller 46, in some embodiments, controls the temperature of thecirculating fluid using closed-loop feedback from temperature sensor 42.That is, controller 46 determines (or receives) a target temperature ofthe fluid, compares it to the measured temperature from sensor 42, andissues a command to heat exchanger 38 that seeks to decrease thedifference between the desired fluid temperature and the measured fluidtemperature. In some embodiments, the difference between the fluidtarget temperature and the measured fluid temperature is used as anerror value that is input into a conventional Proportional, Integral,Derivative (PID) control loop. That is, controller 46 multiplies thefluid temperature error by a proportional constant, determines thederivative of the fluid temperature error over time and multiplies it bya derivative constant, and determines the integral of the fluidtemperature error over time and multiplies it by an integral constant.The results of each product are summed together and converted to aheating/cooling command that is fed to heat exchanger 38 and tells heatexchanger 38 whether to heat and/or cool the circulating fluid and howmuch heating/cooling power to use.

When thermal control unit 22 is operating in the automatic mode,controller 46 may use a second closed-loop control loop that determinesthe difference between a patient target temperature and a measuredpatient temperature. The patient target temperature is input by a userof thermal control unit 22 using control panel 60. The measured patienttemperature comes from a patient temperature probe 68 coupled to one ofpatient temperature sensor ports 66 (FIG. 2 ). Controller 46 determinesthe difference between the patient target temperature and the measuredpatient temperature and, in some embodiments, uses the resulting patienttemperature error value as an input into a conventional PID controlloop. As part of the PID loop, controller 46 multiplies the patienttemperature error by a proportional constant, multiplies a derivative ofthe patient temperature error over time by a derivative constant, andmultiplies an integral of the patient temperature error over time by anintegral constant. The three products are summed together and convertedto a target fluid temperature value. The target fluid temperature valueis then fed to the first control loop discussed above, which uses it tocompute a fluid temperature error.

It will be understood by those skilled in the art that other types ofcontrol loops may be used. For example, controller 46 may utilize one ormore PI loops, PD loops, and/or other types of control equations. Insome embodiments, the coefficients used with the control loops may bevaried by controller 46 depending upon the patient's temperaturereaction to the thermal therapy, among other factors. One example ofsuch dynamic control loop coefficients is disclosed in commonly assignedU.S. patent application Ser. No. 62/577,772 filed on Oct. 27, 2017, byinventors Gregory Taylor et al. and entitled THERMAL SYSTEM WITHMEDICATION INTERACTION, the complete disclosure of which is incorporatedherein by reference.

Regardless of the specific control loop utilized, controller 46implements the loop(s) multiple times a second in at least oneembodiment, although it will be understood that this rate may be variedwidely. After controller 46 has output a heat/cool command to heatexchanger 38, controller 46 takes another patient temperature reading(from probe 68) and/or another fluid temperature reading (from sensor42) and re-performs the loop(s). The specific loop(s) used, as notedpreviously, depends upon whether thermal control unit 22 is operating inthe manual mode or automatic mode.

It will also be understood by those skilled in the art that the outputof any control loop used by thermal control unit 22 may be limited suchthat the temperature of the fluid delivered to thermal pads 24 neverstrays outside of a predefined maximum or a predefined minimum. Thepredefined maximum and minimum are used in order to ensure patientsafety and to avoid delivering fluid that is either too hot or too coldfor patient safety.

Control unit 22 may also be modified to include one or more flow sensorsthat measure the rate of fluid flow and report this information tocontroller 46. In such modified embodiments, controller 46 uses the flowrate in determining what control signals to send to heat exchanger 38and/or pump 32.

It will be understood by those skilled in the art that the particularorder of the components along circulation channel 34 of control unit 22may be varied from what is shown in FIG. 2 . For example, although FIG.2 depicts pump 32 as being upstream of heat exchanger 38 and airseparator 54 as being downstream of heat exchanger 38, this order may bechanged. Air separator 54, pump 32, heat exchanger 38 and reservoir 58may be positioned at any suitable location along circulation channel 34.Indeed, in some embodiments, reservoir 58 is moved so as to be in linewith and part of circulation channel 34, rather than external tocirculation channel 34 as shown in FIG. 2 , thereby forcing thecirculating fluid to flow through reservoir 58 rather than aroundreservoir 58.

Still further, in some embodiments, circulation channel 34 may bemodified so as to allow controller 46 to selectively move reservoir 58into, and out of, circulation channel 34. Such modifications may includethe addition of a reservoir valve (not shown) between air separator 54and valve 56. When the reservoir valve is open, fluid from air separator54 flows along circulation channel 34 to pump 32 without passing throughreservoir 58. When the reservoir valve is closed, fluid coming from airseparator 54 is diverting along a channel that leads into reservoir 58.Fluid inside of reservoir 58 then flows back into circulation channel 34via valve 56. Once back in circulation channel 34, the fluid flows topump 32 and is pumped to the rest of circulation channel 34 and thermalpads 24 and/or bypass line 48. Controller 46 may control the reservoirvalve in order to bring about quicker changes in the temperature of thecirculating fluid, and may do so through the use of a reservoirtemperature sensor that senses the temperature of the fluid inside ofreservoir 58. Further details of one manner of implementing such areservoir valve, as well as controlling it in order to effectuate rapidfluid temperature changes, are disclosed in commonly assigned U.S.patent application Ser. No. 62/610,319 filed Dec. 26, 2017, by inventorsGregory S. Taylor et al. and entitled THERMAL SYSTEM WITH OVERSHOOTREDUCTION, the complete disclosure of which is incorporated herein byreference.

FIG. 3 illustrates in greater detail the coupling of hoses 26 betweenthermal control unit 22 and thermal pads 24. As shown therein, each hose26 is comprised of an intermediate segment 70 and a thermal pad segment72. Each intermediate hose segment 70 includes two ends 74 a and 74 b. Aconnector 76 is coupled to each end 74 a and 74 b. Connectors 76 areadapted to releasably couple intermediate hose segment 70 to otherstructures. Specifically, connectors 76 on first end 74 a ofintermediate hose segments 70 are adapted to releasably couple to outletports 44 and inlet ports 52 of thermal control unit 22. Connectors 76 onsecond end 74 b of intermediate hose segments 70 are adapted toreleasably couple to mating connectors 78 that are integrated withthermal pad hose segments 72.

Connectors 78 of thermal pads 24 are integrally coupled to thermal padhose segments 72. That is, connectors 78 are not able to be decoupledfrom thermal pad hose segments 72 without damaging hose segment 72.Similarly, thermal pad hose segments 72 are integrally coupled to a mainbody portion 80 of thermal pads 24. Such hose segments 72 cannot bedecoupled from the thermal pad body portions 80 without damaging thethermal pad 24. Connectors 76 and 78 may be any suitable commerciallyavailable connector that allows hose segments 70 and 72 to be easilyfluidly coupled and decoupled. In some embodiments, connectors 76 and 78may be what is commonly referred to as “Colder style” connectors. Othertypes of connectors, however, can be used.

In practice, intermediate hose segments 70 are typically not disposable,but instead are re-used from patient to patient. Thermal pad hosesegments 72, however, are typically discarded after a patient'streatment has finished. This is because thermal pads 24 are typicallydiscarded after use with a single patient, and thermal pad hose segments72 are an integral part of the thermal pads 24. Consequently, wheneverthermal control system 20 is used with a new patient, the new patienttypically has his or her torso and legs wrapped with a new set ofthermal pads 24.

In the embodiment of thermal pads 24 shown in FIG. 3 , each thermal pad24 includes a filter 82 positioned inside of each of the thermal padhose segments 72. Filters 82 are adapted to filter particles from thefluid circulating to and from thermal pads 24, which is typically water,although it will be understood that other liquids may be used, includingnon-water based mixtures. The particles filtered by filters 82 include,but are not limited to, microbes and other potentially infectiousagents. In some embodiments, filters 82 have pore sizes of 0.2 micronssuch that the majority of particles passing therethrough are smallerthan 0.2 microns in size. In other embodiments, filters 82 may havedifferent port sizes.

In the embodiment shown in FIG. 3 , each thermal pad includes twofilters 82 positioned in both of the thermal pad hose segments 72 ofeach thermal pad 24. It will be understood that this may be modified ina number of different manners. For example, in some modified embodimentsof thermal pad 24, only a single one of the hose segments 72 of eachthermal pad 24 includes a filter 82. This single filter may bepositioned in either the inlet hose segment 72 or the outlet hosesegment 72 of the thermal pad 24. In another modified embodiment, one ormore additional filters 82 are included within the main body portion 80of thermal pad 24. The inclusion of one or more additional fluid filters82 within main body portion 80 may be implemented where both hosesegments 72 (inlet and outlet) of thermal pad 24 include a filter 82, orit may be implemented where only a single one of hose segments 72 (inletor outlet) of thermal pad 24 include a filter 82.

In still other embodiments, thermal control system 20 may be modified toinclude one or more filters 82 positioned inside of one or both of theintermediate hose segments 70 that coupled to a particular thermal pad24. Such filters 82 may be in lieu of, or in addition to, any filters 82that are positioned inside of the main body 80 of thermal pads 24 and/orinside thermal pad hose segments 72. However, it will be understood thatpositioning filters 82 inside of thermal pad segments 72 and/or the mainbodies 80 of thermal pads 24, rather than intermediate hose segments 70,has the advantage that the filters 82 are then disposed of whenever anew thermal pad 24 is used with system 20. This relieves the user ofthermal control system 20 of having to perform the separate job ofchanging a filter.

It will be understood by those skilled in the art that the use offilters 82 in thermal pads 24 (hose segments 72 and/or main bodies 80)allows thermal control unit 22 to be constructed without any internalfilters, thereby relieving the user of the need to change or replacefilters within thermal control unit 22. Instead, fresh filters 82 areautomatically provided whenever a new patient is used with thermalcontrol system 20 who receives a new set of thermal pads 24.

In still another modified embodiment of thermal control system, thermalcontrol unit 22 includes an internal fluid filter 82 and thermal pads 24also include one or more fluid filters (located in main body 80 and/orhose segments 72). In this embodiment, thermal control unit 22 includesa filter 82 that has a smaller pore size than the filters 82 includedwithin the thermal pads 24. The larger pore size of the filters 82 inthe thermal pads 24 removes the larger particles from the fluid, therebyhelping to prevent the smaller pore sized filter 82 within thermalcontrol unit 22 from becoming clogged. This tends to prolong the life ofthe smaller pore sized filter 82 contained within thermal control unit22, thereby reducing the frequency at which the smaller pore-sizedfilter 82 within thermal control unit 22 needs to be replaced. Further,because smaller pore sized filters tend to more expensive than largerpore sized filters, this arrangement prolongs the life of the moreexpensive filter 82 within thermal control unit 22 while causing theless expensive filters 82 within the thermal pads 24 to be discarded.The use of less expensive filters 82 within thermal pads 24, of course,also tends to reduce the price of the thermal pads 24 relative tocomparable thermal pads 24 having smaller pore sized filters.

In the aforementioned embodiment of thermal control system 20 wherethermal control unit 22 includes a smaller pore sized filter 82 than thefilters 82 within thermal pads 24, it may be advantageous to locate thesmaller pore sized filter 82 within inlet manifold 50, or between inletmanifold 50 and the downstream end of bypass line 48. By selecting oneof these locations, the internal filter 82 within thermal control unit22 only receives and filters liquid that has already passed throughthermal pads 24 and their associated filters 82. The internal filter 82within thermal control unit 22 therefore only filters liquid that hasbeen pre-filtered by the larger pore filters 82 of thermal pads 24.These larger pore filters 82 remove most of the larger particles fromthe fluid traveling through the internal filter 82, thereby prolongingthe life of the relatively more expensive filter 82 that is internal tothermal control unit 22.

FIG. 4 illustrates in greater detail one manner of constructing thermalpads 24. As shown therein, main body portion 80 of thermal pad 24includes a first sheet 84, a second sheet 86, and an insulating sheet88. First sheet 84 is adapted to face toward a patient and, in someinstances, be placed in physical contact with the patient whenundergoing thermal therapy. Second sheet 86 is adapted to face away fromthe patient during thermal therapy. Insulating sheet 88 is an optionalsheet that, when included, is adapted retard the flow of thermal energybetween the fluid circulating within main body 80 of thermal pad 24 andits ambient surroundings.

First sheet 84 and second sheet 86 may be constructed from a variety ofdifferent materials. In some embodiments, first and second sheets 84 and86 are constructed from a polyester and/or nylon composite. Othermaterials that are suitably flexible to allow sheets 84 and 86 to bewrapped around a patient and that have relatively good thermalconductivity, however, may be used. Insulation sheet 88 may beconstructed from any suitably flexible material that has relatively poorthermal conductivity properties so as to thermally insulate the othersheets (and the fluid contained therein) from the temperature of theambient surroundings. In some embodiments, insulation sheet 88 isconstructed from material that includes a polyester foam, or other typeof foam. Still other constructions are possible.

First and second sheets 84 and 86 are bonded to each other by aperipheral seal 87 that extends about their respective peripheries. Suchbonding may be accomplished in any suitable manner provided the bondingforms a liquid impermeable bond. In some embodiments, the bonding iscarried out using welds. Such welds may be implemented via heat welding,ultrasonic welding, Radio Frequency (RF) welding, or by other types ofwelding. In addition to being bonded to each other around theirperimeters, first and second sheets 84 and 86 are bonded to each otherat a plurality of internal locations 90 (not visible in FIG. 4 , butshown in FIG. 5 ) (FIG. 4 ). Such bonding may also be carried out in anysuitably manner, including by use of one or more of the weldingtechniques mentioned above. The space between first and second sheets 84and 86 where they are not bonded to each other defines a fluid chamberin which the temperature controlled fluid supplied by thermal controlunit 22 (via supply hose 26 a) circulates.

In some regions of thermal pad 24, the bonding locations 90 arecontiguous with each other to create one or more fluid passageway walls(not shown) within thermal pad 24. Such walls guide the fluid as itcirculating within the main body portion 80 of thermal pads 24. In someembodiments, one or more of such walls may be included that dividethermal pad 24 into one or more fluidly isolated zones, such asdisclosed in commonly assigned U.S. patent application Ser. No.62/373,564 filed Aug. 11, 2016, by inventors James Galer et al. andentitled THERMAL SYSTEM, the complete disclosure of which isincorporated herein by reference.

In some embodiments, first sheet 84 may be comprised of, or haveattached to it, a gel layer that is adapted to releasably adhere to theskin of the patient and thereby maintain contact with the patient's skinduring the course of thermal therapy. The particular gel material usedmay vary. In some embodiments, the gel is a urethane gel. The specificchemical composition of the urethane gel can be adjusted to change theadhesive properties of the side of sheet 84 that contacts the patient'sskin. When first sheet 84 includes gel, it may be secured thereto by RFwelding, lamination, by being poured thereon, or by other means.Regardless of the specific gel used and the specific manner it issecured to first sheet 84, the gel should provide suitable adhesion tothe surface of the patient's skin in order to resist physical separationbetween the pad 24 and the patient, yet not be so resistant to physicalseparation so as to cause discomfort to the patient when the pad 24 issubsequently removed.

In some embodiments, thermal pad 24 is modified to include additionalsheets or layers beyond those shown in FIG. 4 . When such additionallayers are included, multiple fluid chambers may be defined within athermal pad 24. Examples of such multi-chamber thermal pads aredisclosed in commonly assigned U.S. patent application Ser. No.62/373,658 filed Aug. 11, 2016, by inventors James Galer et al. andentitled THERMAL THERAPY DEVICES, the complete disclosure of which isincorporated herein.

Although not shown, thermal pad 24 may also include one or more strapsthat are used to secure thermal pad 24 to patient 30 when in use. Eachstrap may be adapted to releasably attach to another strap after thermalpad 24 has been wrapped around the patient 30. In some embodiments, thestraps include hook and loop type fasteners, such as those sold underthe tradename Velcro, while in other embodiments, the straps include oneor more repositionable tapes. In other embodiments, the straps includeother types of fasteners for securing themselves to each other in orderto maintain pad 24 in a wrapped stated around the patient's leg ortorso.

Although thermal pads 24 are depicted in FIGS. 3 and 4 as havinggenerally rectangular shapes, it will be understood by those skilled inthe art that this may be varied greatly. That is, thermal pad 24 maytake on any shape that is conducive to being wrapped around one or moreportions of patient 30. In some embodiments, those thermal pads 24 thatare intended to be wrapped around the patient's torso have a differentshape than those intended to be wrapped around the patient's legs. Thoseadapted to be wrapped around the patient's legs may include one or morecutouts or contours that allow the patient to bend his or her kneeswhile thermal pads 24 are wrapped around his or her legs.

FIGS. 5 and 6 illustrate an alternative embodiment of a thermal pad 124that may be used with thermal control system 20 in place of one or moreof thermal pads 24. Thermal pad 124 includes a number of components thatare common to thermal pads 24 and those components are provided with thesame reference number. Unless otherwise stated explicitly below, thecommon components are constructed and operate in the same mannerpreviously described, serve the same functions previously described, andmay be modified in any one or more of the previously described manners.Thermal pad 124 also includes one or more components that are similar tocomponents of thermal pad 24 but modified in some manner. Such modifiedcomponents are labeled with the same reference number increased by onehundred. Those components of thermal pad 124 that are not found inthermal pad 24 and/or that were not previously described or assigned areference number are provided with a new reference number.

Thermal pad 124 differs from thermal pad 24 primarily in the location ofits filter (FIGS. 5-6 ). More specifically, thermal pad 124 includes afilter 182 positioned inside of main body 80 and no filters includedwithin hose segments 72. Filter 182 is a generally flat sheet that issandwiched between first sheet 84 and second sheet 86. Filter sheet 182is secured to first and second sheets 84 and 86 about its periphery, aswell as at bonding locations 90. An interior fluid chamber 100 isdefined between the first and second sheets 84 and 86 in those locationswhere first and second sheets 84 and 86 are not bonded together. Filtersheet 182 essentially divides fluid chamber 100 into two halves: anupper half 102 a and a lower half 102 b. Filter sheet 182 includes a topsurface 92 that faces toward second sheet 86 and a bottom surface 94that faces toward first sheet 84. Upper half 102 a of fluid chamber 100is defined between top surface 92 of filter sheet 182 and the interiorside of second sheet 86. Lower half 102 b of fluid chamber 100 isdefined between bottom surface 94 of filter sheet 192 and the interiorside of first sheet 84.

Filter sheet 182 is arranged such that fluid entering an inlet 96 (e.g.a first one of hose segments 72) enters lower half 102 b of fluidchamber 100 and fluid exiting an outlet 98 (e.g. a second one of thehose segments 72) exits out of the upper half 102 a of fluid chamber100. Accordingly, in order for fluid entering inlet 96 to exit out ofoutlet 98, the fluid must pass from lower half 102 b through filtersheet 182 to upper half 102 a. Filter sheet 182 therefore filters allwater passing through thermal pad 124. Filter 182, in some embodiments,is made of a material that stretches in response to the fluid pressureless than the material of first and second sheets 84 and 86. The fluidpressure therefore does not stretch filter 182 such that it abutsagainst first or second sheet 84 or 86, but instead allows filter 182 toremain generally spaced apart from both sheets 84 and 86 (at locationsother than bonding locations 90 and its peripheral seal).

By utilizing a filter sheet 182 having a surface area substantiallyequal to the planar footprint of first and second sheets 84 and 86,filter sheet 182 is able to provide a filtering surface having asignificantly large surface area, thereby allowing fluid to passtherethrough at a large number of locations, and thereby also extendingthe life of the filter when compared to a filter having a smallersurface area.

Thermal pad 124 includes a number of interior walls 104 that define aplurality of fluid passageways 106. In the embodiment shown in FIG. 5 ,walls 104 are defined by a series of bonding locations 90 that arecontiguous with each other. It will be understood that walls 104 may bearranged in any suitable manner and that the particular arrangementshown in FIG. 5 is but one arbitrary example of such an arrangement.Temperature controlled fluid supplied to thermal pad 124 via inlet 96(which couples to a fluid supply hose 26 a of thermal control unit 22)flows into a passageway 106 that follows a tortuous path to outlet 98.With reference to the orientation of main body 80 as depicted in FIG. 6, passageway 106 extends up and down past a series of three walls 104before terminating at a corner of main body 80 adjacent outlet 98. Theinclusion of one or more passageways 106 within main body 80 helps toensure that the fluid delivered to thermal pad 24 is circulatedthroughout the entire interior of thermal pad 24 before being returnedto thermal control unit 22.

It will be understood by those skilled in the art that the particularorientation of thermal pad 124 shown in FIG. 6 and the descriptors usedherein to describe that orientation (e.g. “upper” and “lower”) arearbitrary. That is, for example, although FIG. 6 depicts inlet 96entering into lower half 102 b of fluid chamber 100, thermal pad 124could be modified to have inlet 96 enter into upper half 102 a and exitout of lower half 102 b. It will also be appreciated that thermal pad124 can be modified to include additional layers, such as, but notlimited to, a nonwoven insulation sheet 88 and/or one or more otherlayers.

FIG. 7 illustrates a modified embodiment of a thermal pad 124 a that maybe used with thermal control system 20 in place of one or more ofthermal pads 24 and/or 124. Thermal pad 124 a includes a number ofcomponents that are common to thermal pads 24 and/or 124 and suchcomponents are provided with the same reference number. Unless otherwisestated explicitly below, the common components are constructed andoperate in the same manner previously described, serve the samefunctions previously described, and may be modified in any one or moreof the previously described manners. Thermal pad 124 a also includes oneor more components that are similar to components of thermal pad 24and/or 124, but modified in some manner. Such modified components arelabeled with the same reference number followed by the letter “a.” Thosecomponents of thermal pad 124 a that are not found in thermal pads 24 or124 and/or that were not previously described or assigned a referencenumber are provided with a new reference number.

Thermal pad 124 a differs from thermal pad 124 in that its filter 182has been supplemented with two additional filters 182 a and 182 b. Thatis, thermal pad 124 a includes, in addition to filter 182, a first outerfilter 182 a, and a second outer filter 182 b. First outer filter 182 ais positioned on a first side of filter 182 and second outer filter 182b is positioned on a second side of filter 182 opposite the first side.In this manner, filter 182 is sandwiched between outer filters 182 a and182 b such that fluid flowing through filter 182 (in the direction frominlet 96 to outlet 98) must first flow through first outer filter 182 abefore reaching filter 182. After passing through filter 182, the fluidmust then flow through second outer filter 182 b before it is able toexit out of outlet 98. In at least one embodiment, first and secondouter filters 182 a and 182 b are laminated on opposite sides of filter182. In other embodiments, one or more of first and second outer filters182 a and/or 182 b may be spaced apart from filter 182.

Regardless of the specific physical arrangement of filters 182, 182 a,and 182 b, the outer filters 182 a and 182 b are selected to include alarger pore size than the pore size of filter 182 that is positionedbetween them. Thus, the outer filters 182 a and 182 b allow largerparticles to pass through them than are able to pass through theintermediate filter 182. Outer filters 182 a and/or 182 b therefore actas pre-filters and filter out larger suspended particulates from thefluid before the fluid is able to pass through filter 182. This reducesthe amount of particulate build-up that might otherwise occur on filter182, thereby extending the useful life of filter 182. In someembodiments, filter 182 is a 0.2 micron filter adapted to substantiallyfilter out particles having a size larger than 0.2 microns, and outerfilters 182 a and/or 182 b are filters with a larger pore size than 0.2microns. In many embodiments, outer filters 182 a and 182 b have thesame pore size rating.

By including two outer filters 182 a and 182 b, thermal pad 124 aensures that the fluid flowing therethrough is always pre-filtered byeither outer filter 182 a or 182 b, regardless of which direction thefluid flows through pad 124 a. That is, thermal pad 124 a is configuredto be agnostic as to the direction of fluid flow so that a user cancouple either inlet 96 to outlet port 44 of thermal control unit 22, oroutlet 98 to outlet port 44 of thermal control unit 22. By beingdirection agnostic, the user does not have to concern himself or herselfwith which end (outlet/inlet) of thermal pad 124 a he or she couples tooutlet ports 44 of thermal control unit 22 because one of the outerfilters 182 a or 182 b will always pre-filter the fluid before itreaches filter 182. This makes the coupling of thermal pad 124 a tothermal control unit 22 easier. However, if thermal pad 124 a were to bemodified such that a specific one of its connectors 78 needed to becoupled to outlet port 44 and the other connector 78 needed to becoupled to inlet port 52, thereby ensuring that fluid always flowedthrough pads 124 a in a known and constant direction, pad 124 a could bemodified, if desired, to include only one of the outer filters 182 a or182 b (whichever one is upstream of filter 182). In such embodiments,the outer filter 182 a or 182 b that was downstream of filter 182 (whichhas a smaller pore size) could be omitted because such a downstreamfilter would not serve an evident purpose.

FIGS. 8-10 illustrate an alternative embodiment of a thermal pad 224that may be used with thermal control system 20 in place of one or moreof thermal pads 24 and/or 124. Thermal pad 224 includes a number ofcomponents that are common to thermal pads 24 and/or 124 and suchcomponents are provided with the same reference number. Unless otherwisestated explicitly below, the common components are constructed andoperate in the same manner previously described, serve the samefunctions previously described, and may be modified in any one or moreof the previously described manners. Thermal pad 224 also includes oneor more components that are similar to components of thermal pad 24and/or 124, but modified in some manner. Such modified components arelabeled with the same reference number increased into the two hundredrange. Those components of thermal pad 224 that are not found in thermalpads 24 or 124 and/or that were not previously described or assigned areference number are provided with a new reference number.

Thermal pad 224 differs from thermal pad 124 primarily in the size ofits filter 282 (FIGS. 8-10 ). More specifically, instead of a filtersheet extending over substantially the entire area of main body portion80, such as filter 182 does in thermal pad 124, filter sheet 282 extendsover approximately only a quarter of the surface area of main bodyportion 80. Filter sheet 282 otherwise functions in the same manner asfilter sheet 182. That is, fluid entering inlet 96 enters a lower half102 b of fluid chamber 100. In order for the fluid to exit out of outlet98 of main body portion 80, the fluid must travel to the upper half 102a of fluid chamber 100, which means the fluid must pass through filter282. Accordingly, filter 282 filters the fluid as it circulates throughmain body portion 200.

Filter 282 is bonded to both first and second sheets 84 and 86 along itstop edge 108 a, its bottom edge 108 b, and its first side 108 c (FIG. 8). Filter 282 is also bonded to both first and second sheets 84 and 86at bonding locations 90. Still further, filter 282 is bonded to firstand second sheets 84 and 86 along a portion of its second side 108 dthat coincides with the upstream-most wall 104 within main body portion80. In a region 110 of second side 108 d between wall 104 and top edge108 a, filter 282 is bonded to only first sheet 84, but not to secondsheet 86, as shown more clearly in FIG. 10 . By bonding filter sheet 282to first sheet 84 in this region 110, any fluid that is in lower half102 b of fluid chamber 100 must pass through filter 282 before travelingdownstream of region 110, thereby ensuring that all fluid travelingdownstream of region 110 is filtered.

It will be understood that the arrangement of outlet 98 and the bondingof filter sheet 282 within region 110 can be reversed from what is shownin FIGS. 8-10 . That is, instead of having inlet 96 in direct fluidcommunication with lower half 102 b of fluid chamber 100, inlet 96 couldbe modified to enter into upper half 102 a of fluid chamber 100. Such amodification would be accompanied by changing the bonding of filter 282in region 110. Specifically, when inlet 96 is modified to enter intoupper half 102 a, filter 282 is bonded to second sheet 86, rather thanfirst sheet 84, in region 110. This alteration ensures that fluid cannotbypass filter 282 as it flows through passageways 106 toward outlet 98.

It will be understood that the particular size, shape, and location offilter 282 shown in FIGS. 8-10 can be varied significantly. For example,filter 282 may be placed toward the downstream end of main body 80, orit may be placed in a middle region of main body 80. Alternatively, oradditionally, filter 282 may have a non-square shape and may beimplemented in some embodiments as either larger or smaller. Stillfurther, as with all of the filters disclosed herein that are positionedinside of main body 80, it can be combined with one or more filterspositioned in hoses 26 (in segment(s) 72 and/or 74) and/or additionalfilters positioned within main body 80 (e.g. one or more outer filters,such as filters 182 a and/or 182 b, may added in a manner similar tothat described above with respect to thermal pad 124 a). As describedabove, in any of the embodiments having three or more filters, it may bebeneficial to arrange the filter with the smallest pore size between theother two (or more) filters (which may have a common filter pore size)so that the other two filters remove the bulk of the larger particles,thereby extending the life of the smaller-pored filter. Further, asnoted previously, by constructing the two other filters so as to have acommon pore size, the thermal pad can be coupled to thermal control unit22 in a direction-agnostic manner (e.g. supply hose 26 a can be coupledto inlet 96 or to outlet 98 with return hose 26 b coupled to the otherof the inlet 96 or outlet 98).

FIGS. 11-13 illustrate an alternative embodiment of a thermal pad 324that may be used with thermal control system 20 in place of one or moreof thermal pads 24, 124, and/or 224. Thermal pad 324 includes a numberof components that are common to thermal pads 24, 124, and/or 224 andsuch components are provided with the same reference number. Unlessotherwise stated explicitly below, the common components are constructedand operate in the same manner previously described, serve the samefunctions previously described, and may be modified in any one or moreof the previously described manners. Thermal pad 324 also includes oneor more components that are similar to components of thermal pad 24,124, and/or 224, but modified in some manner. Such modified componentsare labeled with the same reference number increased into the threehundred range. Those components of thermal pad 324 that are not found inthermal pads 24, 124, or 224 and/or that were not previously describedor assigned a reference number are provided with a new reference number.

Thermal pad 324 differs from the previously described thermal padsprimarily in the shape of its filter 382 (FIGS. 11-13 ). Morespecifically, instead of a substantially planar sheet, such as filters82, 182, and 282, filter 382 is a bag shaped filter having an interior111 a and an exterior 111 b. Interior 111 a is defined between a topfilter sheet 112 a and a bottom filter sheet 112 b. Top and bottomfilter sheets 112 a and 112 b are secured to each other about theirentire periphery except for a small region where inlet 96 is defined. Ascan be seen in FIG. 12 , top and bottom filter sheets 112 a and 112 bmay also be secured to each other at bonding locations 90 where firstand second sheets 84 and 86 are bonded to each other. At locations 90,top and bottom filter sheets 112 a and 112 b are secured together by thebonding of first and second sheets 84 and 86.

In the particular embodiment illustrated in the drawings, filter 382 ispositioned such that fluid entering into main body 80 from inlet 96enters into the interior 111 a of filter 382. In order for the fluid toescape out of the interior 111 a into the exterior 111 b, the fluid mustpass through filter 382. The passage of fluid through either top orbottom filter sheet 112 a or 112 b filters out particulates having alarger size than the pore sizes of the filter sheets 112 a or 112 b,which, in at least some embodiments, is 0.2 microns or smaller.

Interior 111 a defines a fluid channel 114 that extends into main body80 for approximately one quarter of the length of main body 80. It willbe understood that filter 382 may be modified to extend farther orshorter distances into main body 80 than what is shown in FIG. 11 .Expanding the extent of filter 382 provides a greater surface area forthe fluid to flow through, while reducing the extent of filter 382 intomain body 80 reduces the surface area for the fluid to flow through. Insome embodiments, top fluid sheet 112 a may be bonded to bottom fluidsheet 112 b at one or more additional locations (beyond theirperipheries and bonding locations 90). Such additional bonding mayinclude continuous bonds that define one or more walls within bag shapedfilter 382. Such filter walls may be selected to better control the flowof fluid through filter 382 and/or main body 80. Thermal pad 324 mayfurther be modified to include multiple bag shaped filters 382, eitherin addition to, or in lieu of, any of the aforementioned modifications.

In still other modified embodiments of thermal pad 324, one or more foamor other resilient, but fluid permeable, materials may be positionedinside the interior region 111 a of one or more of the one or morebag-shaped filters 382. Such materials may be positioned therein inorder to prevent the bag-shaped filter from collapsing on itself if thethermal pad 324 is coupled to thermal control unit 22 in such a way thatfluid flows in the opposite direction to what is shown in FIG. 12 . Thatis, if fluid flows from the exterior region 111 b into the interiorregion 111 a (which is opposite to what is shown in FIG. 12 ), the fluidpressure may tend to collapse bag-shaped filter 382. By including aresilient, but fluid permeable material within interior region 111 a,such collapse is reduced or eliminated. Such resilient material, in someembodiments, enables thermal pad 324 to be coupled to thermal controlunit 22 in a manner that is agnostic as to the direction of the fluidflow. In other embodiments, thermal pad 324 may include two bag-shapedfilters 382—one coupled to the inlet 96 and one coupled to the outlet98, and either one of both of the filters 382 may include or omit suchresilient material.

FIGS. 14-16 illustrate an alternative embodiment of a thermal pad 424that may be used with thermal control system 20 in place of one or moreof thermal pads 24, 124, 224, and/or 324. Thermal pad 424 includes anumber of components that are common to thermal pads 24, 124, 224,and/or 324 and such components are provided with the same referencenumber. Unless otherwise stated explicitly below, the common componentsare constructed and operate in the same manner previously described,serve the same functions previously described, and may be modified inany one or more of the previously described manners. Thermal pad 424also includes one or more components that are similar to components ofthermal pad 24, 124, 224, and/or 324, but modified in some manner. Suchmodified components are labeled with the same reference number increasedinto the four hundred range. Those components of thermal pad 424 thatare not found in thermal pads 24, 124, 224, or 324 and/or that were notpreviously described or assigned a reference number are provided with anew reference number.

Thermal pad 424 differs from thermal pad 224 (FIG. 8 ) in that itincludes two additional filters. Specifically, thermal pad 424 includesa filter 482, as well as a first outer 482 a and a second outer filter482 b (FIGS. 14-16 ). Filters 482, 482 a, and 482 b are similar tofilters 182, 182 a, and 182 b of thermal pad 124 (FIG. 6 ) except thatfilters 482, 482 a, and 482 b are spaced apart from each other andpositioned in different locations of body 80 of thermal pad 424. Despitethese different locations, filters 482, 482 a, and 482 b act in asimilar manner to filters 182, 182 a, and 182 b. That is, outer filters482 a and 482 b act as pre-filters to filter 482 and filter largerparticles out of the fluid before they reach filter 482, therebyreducing the number of particles that would otherwise accumulate infilter 482 and thus extending the life of filter 482. As with outerfilters 182 a and 182 b, outer filters 482 a and 482 b are selected tohave a larger pore size than filter 482. In some embodiments, filter 482has a pore size adapted to substantially filter out particles having adiameter greater than 0.2 microns, while filters 482 a and 482 b areconstructed with a greater pore size.

As can be seen more clearly in FIGS. 15 and 16 , when fluid enters inlet96 of thermal pad 424, it enters into lower half 102 b of fluid chamber100. In order for the fluid to move into a first zone 120 (FIG. 14 ) ofbody 80, the fluid must pass through first outer filter 482 a. Once thefluid has entered first zone 120, it must pass through filter 482 beforeentering a second zone 122. Finally, in order for the fluid in secondzone 122 to exit out of outlet 98, it must pass through second outerfilter 482 b. Thermal pad 424 is therefore constructed to ensure thatfluid flowing through body 80 must pass through all three filters 482,482 a, and 482 b before exiting.

Filters 482, 482 a, and 482 b are bonded to both first and second sheets84 and 86 along their top edges 108 a, their bottom edges 108 b, andtheir sides 108 c (FIG. 14 ). Filters 482, 482 a, and 482 b are alsobonded to both first and second sheets 84 and 86 at bonding locations90, as well as along their edges 108 d that are coincident with internalwalls 104. Still further, each of filters 482, 482 a, and 482 b is alsosecured to first sheet 84 and/or second sheet 86 at a plurality ofbonding regions 110. Such bonding regions 110 are positioned along theinner peripheries of first and second zones 120 and 122 and ensure thatfluid is not able to flow around the respective filters. Filter 482 isalso bonded to a center wall 104 a (FIGS. 14 & 16 ).

It will be understood by those skilled in the art that the size andshape of filters 482, 482 a, and 482 b, as well as the size and shape ofbonding regions 110 may vary from what is shown in FIGS. 14-16 .Further, as with thermal pad 124 a, thermal pad 424 may be modified toinclude only a single outer filter 482 a or 482 b if it is constructedsuch the flow direction of the fluid through the thermal pad 424 isalways known and constant (in such embodiments, the filter 482 a or 482b that is upstream of filter 482 is retained and the downstream filteris omitted).

FIGS. 17-19 illustrate another alternative embodiment of a thermal pad524 that may be used with thermal control system 20 in place of one ormore of thermal pads 24, 124, 224, 324, and/or 424. Thermal pad 524includes a number of components that are common to thermal pads 24, 124,224, 324, and/or 424 and such components are provided with the samereference number. Unless otherwise stated explicitly below, the commoncomponents are constructed and operate in the same manner previouslydescribed, serve the same functions previously described, and may bemodified in any one or more of the previously described manners. Thermalpad 524 also includes one or more components that are similar tocomponents of thermal pad 24, 124, 224, 324, and/or 424, but modified insome manner. Such modified components are labeled with the samereference number increased into the five hundred range. Those componentsof thermal pad 524 that are not found in thermal pads 24, 124, 224, 324,or 424 and/or that were not previously described or assigned a referencenumber are provided with a new reference number.

Thermal pad 524 differs from the previously described thermal pads inits shape and the locations of its inlet 96 and outlet 98 relative toits body 80, as well as in other respects. Thermal pad 524 includes acentral region 517, a pair of wings 518, and one or more fasteners 519(e.g. hook and loop fasteners, straps, etc.). Central region 517 isintended to be positioned underneath the torso region of a patient (e.g.in contact with the patient's back). Wings 518 are intended to bewrapped around and over the abdominal region of the patient and securedtogether via the one or more fasteners 519. Central region 517 may alsobe dimensioned to come into physical contact with all or a portion ofthe back of a patient's neck. It will be understood that the shapeand/or size of thermal pad 524 may be varied from what is shown in FIG.17 . It will also be understood that thermal pad 524 may be used inother regions of a patient's body besides the torso region, such as, butnot limited to, the patient's legs, arms, neck, and/or head.

Thermal pad 524 includes an inlet 96 and an outlet 98 that arepositioned adjacent to each other. Inlet 96 allows fluid to flow into afluid passageway 106 that extends throughout thermal pad 524 betweeninlet 96 and outlet 98. A filter 582 (FIGS. 18 and 19 ) is includedwithin body 80 of thermal pad 524 and extends over the entire area ofbody 80. That is, filter 582 is a sheet-like filter that generallydefines a plane parallel to a plane generally defined by sheets 84 and86. The peripheral boundaries of filter 582 generally match, and aresealed to, the peripheral boundaries of body 80. More specifically,filter 582 is bonded at a peripheral seal 87 to first and second sheets84 and 86. Filter 582 is also bonded to sheets 84 and 86 at internalwalls 104 and at bonding locations 90.

As can be seen more clearly in FIGS. 18 and 19 , filter 582 ispositioned with respect to inlet 96 and outlet 98 such that fluidentering into body 80 from inlet 96 enters on a first side of filter 582and fluid exiting out of body 80 via outlet 98 is on the second andopposite side of filter 582. Thus, fluid entering into body 80 ofthermal pad 524 via inlet 96 must pass through filter 582 before exitingout of outlet 98. FIG. 19 illustrates first sheet 84 and second sheet 86separated from each other with filter sheet 582 positioned therebetween.As shown therein, it can be seen that filter 582 is positioned overinlet 96 and underneath outlet 98.

FIG. 20 illustrates yet another alternative embodiment of a thermal pad624 that may be used with thermal control system 20 in place of one ormore of the previously discussed thermal pads (e.g. 24-524). Thermal pad624 includes a number of components that are common to these previouslydiscussed thermal pads and those components are provided with the samereference number. Unless otherwise stated explicitly below, the commoncomponents are constructed and operate in the same manner previouslydescribed, serve the same functions previously described, and may bemodified in any one or more of the previously described manners. Thermalpad 624 also includes one or more components that are similar to one ormore components of the previously discussed thermal pads 24, and suchmodified components are labeled with the same reference number increasedinto the six hundred range. Those components of thermal pad 624 that arenot found in the previously discussed thermal pads are provided with anew reference number.

Thermal pad 624 differs from the previously described thermal pads inthat it includes a filter 682 that is alternately bonded to first sheet84 and second sheet 86. This bonding occurs at locations 690. As can beseen in FIG. 20 , this bonding alternates between first sheet 84 andsecond sheet 86. That is, filter sheet 682 is bonded to only one offirst sheet 84 or second sheet 86 at a given bonding location 690, andat the bonding locations 690 adjacent thereto, filter sheet 682 isbonded to the other of the first or second sheets 84 or 86. Thisalternate bonding occurs not only in the lateral directions illustratedin FIG. 20 , but also in the forward and backward directions. In otherwords, the bond 690 between filter 682 and second sheet 86 showngenerally in the middle of FIG. 20 is surrounded not only on its rightand left side by bonds 690 to first sheet 84, but also by bonds behindand in front of it (not shown in FIG. 20 , but extending into and out ofthe plane of FIG. 20 ) that are between filter 682 and first sheet 84.Thus, in this particular embodiment, a given bond 690 to second sheet86, for example, is surrounded by four adjacent bonds 690 to first sheet84 (one on each side, one in front and one behind). Similarly, a givenbond 690 to first sheet 84 is surrounded by four adjacent bonds 690 tosecond sheet 86. Other arrangements of bonds 690 may be utilized,including one or more bonds 690 that bond filter 682 to both first andsecond sheet 84 and 86 at a common location 690. Regardless of theparticular bonding layout selected for a given embodiment, fluidentering thermal pad 624 enters into either upper interior region 102 aor lower interior region 102 b and must pass through filter sheet 682 atsome point in order to exit out of thermal pad 624.

Filter sheet 682 is adapted to perform both a structural function and afiltering function in thermal pad 624 (FIG. 20 ). Filter sheet 682performs the structural function of keeping first and second sheets 84and 86 within a set distance of each other. That is, the pressure of thefluid supplied to thermal pad 624 from thermal control unit 22 tends tourge first and second sheets 84 and 86 apart from each other (firstsheet 84 is urged upward in the sectional view of FIG. 20 and secondsheet 86 is urged downward in FIG. 20 ). This upward and downwardmovement is resisted by filter sheet 682 which limits the distance thetwo sheets 84 and 86 can move apart from each other. Filter sheet 682therefore serves the structural function of keeping thermal pad 624 frombulging beyond a desired limit, as well as filtering the fluid passingthrough main body portion 80.

In the example shown in FIG. 20 , thermal pad 624 includes an insulatingsheet 88 as well as an interior sheet 116. Interior sheet 116 may bemade of a non-woven fabric material that is adapted to come into contactwith a patient's skin. In some embodiments, the non-woven fabricmaterial of interior sheet 116 is impregnated with one or more materialshaving anti-microbial properties. Such materials include, but are notlimited to, copper, silver, zinc, and other anti-microbial metals, bothin pure form (including, but not limited to, nanoparticle and/ornanotube form) and mixed with other components (e.g. silver salts,silver-polymer composites, silver-impregnated zeolites, etc.). Othermaterials also include polyethylene glycol, chitosan, quaternaryammonium compounds, polyethyleneimine, polyguanidines, organosilanes,biguanide-based polymers, and/or halogen-containing polymers. Stillother materials may embedded within insulating sheet 88 in order toreduce and/or eliminate the presence of microbes, as would be known toone of ordinary skill in the art.

It will be understood that thermal pad 624 may also be modified toinclude antimicrobial materials embedded in first sheet 84. The additionof antimicrobial materials within first sheet 84 helps to reduce oreliminate the possibility of microbes living between interior sheet 116and first sheet 84. This is particularly helpful when interior sheet 116is made of a non-woven material that is liquid and/or air permeable andit is possible for particles to enter into the space between interiorsheet 116 and first sheet 84. By including antimicrobial materials infirst sheet 84 and/or interior sheet 116, the risk of transferring aninfectious agent from or to a patient via thermal pad 624 is reduced.

It should also be noted that, by including antimicrobial materialswithin first sheet 84, fluid flowing within fluid chamber 100 will comeinto contact with the interior of first sheet 84 and the antimicrobialproperties embedded therein. Such contact may help to kill microbeswithin the fluid circulating through thermal pad 624. To that end,second sheet 86, in some embodiments, is also embedded withantimicrobial particles. The presence of antimicrobial materials insheets 84 and 86 therefore helps to kill microbes not only on thesurfaces external to these sheets, but also the internal surfaces thatcome into contact with the circulating fluid.

Thermal pad 624 may further be modified to include antimicrobialmaterials embedded within filter 682. Such antimicrobial materials helpto kill any microbes that get trapped within filter 682. Filter 682therefore not only filters out microbes (and any other particlesexceeding its pore size), but also helps to kill the trapped microbes.

In some embodiments, thermal control unit 22 is modified to include oneor more fluid pressure sensors that determine the pressure differencebetween outlet port 44 and inlet 52. In such embodiments, controller 46monitors this pressure difference and, if it exceeds a threshold,provides an alert to the user that the filter within the pad (24, 124,224, etc.) may need to be changed. The threshold is chosen, in at leastsome embodiments, such that controller 46 is able to distinguish betweenhigh pressure differences due to an obstructed filter and high pressuredifferences due to a completely, or nearly completely obstructed thermalpad (the latter generating an even higher pressure difference than theformer). That is, controller 46 is configured, in at least someembodiments, to issue a first alert when a filter should be changed andto issue a second and different alert when the thermal pad iscompletely, or nearly completely, obstructed. In some embodiments,controller 46 determines that the thermal pad is completely, or nearlycompletely, obstructed by monitoring for pressure differences betweenthe outlet and inlet ports 44 and 52 that exceed a second threshold thatis higher than the threshold used to detect an obstructed filter. Inother embodiments, controller 46 determines that the thermal pad iscompletely or nearly completely obstructed by using one or more flowsensors that measure flow rates of fluid exiting outlet port(s) 44and/or entering inlet port(s) 52.

It will be understood by those skilled in the art that any of thefeatures, functions, and/or structures of any of the thermal padsdiscussed herein can be combined with any one or more of the features,functions, and/or structures of any of the other thermal pads discussedherein. Thus, as but one non-limited example, it will be understoodthat, although thermal pad 624 was the only thermal pad discussed abovein which antimicrobial materials may be integrated into its filter, anyof the other thermal pads 24, 124, 224, 324, 424, and/or 524 may utilizeone or more filters having antimicrobial materials integrated therein.As yet another example, although thermal pad 624 was the only thermalpad discussed above having an interior sheet 116, such a sheet may beadded to any of the other thermal pads discussed herein. Still othercombinations of features, functions, and structures are possible andcontemplated by this disclosure.

It will also be understood by those skilled in the art that the previousdiscussions of filter pores and filter ratings may refer to severaldifferent measurements. For example, filters may commonly have a nominalfilter rating, an absolute filter rating, and/or a mean filter rating.In some situations, filters may also or alternatively have a beta ratiorating, which refers to the ratio of the number of particles of aparticular size upstream of the filter compared to the number ofparticles of that particular size downstream of the filter. Theforegoing discussion of filter pores and/or filter ratings may includeany of these potential measurements and/or ratings so long as the fluidthat is filtered by filters 82 (and/or 182, 282, etc.) removes asufficient amount of particles of 0.2 microns or larger after a suitablyshort time duration and/or after a suitably small number of circuitsthrough thermal pads 24. What is considered sufficient and suitable mayvary from application to application, and/or may be dictated by one ormore governing institution, such as, but not limited to, the U.S. Foodand Drug Administration (FDA).

Any of thermal pads 24, 124, 224, etc. discussed above may further bemodified to include one or more sensor layers positioned adjacent tofirst sheet 84. Such a sensing layer includes one or more sensors thatare adapted to be placed in contact with the skin of a patient whosetemperature is to be controlled. The specific type(s) and number ofsensors incorporated into the sensor layer may vary from embodiment toembodiment. In some embodiments, the sensor layer includes at least onesensor that is a tissue oxygenation sensor adapted to detect changes inthe amount of oxygen in the patient's tissue adjacent the sensor.Although different types of tissue oxygenation sensors may be used, onesuitable type is disclosed in commonly assigned U.S. patent applicationSer. No. 14/884,222 filed Oct. 15, 2015, by inventors Marko Kostic etal. and entitled SYSTEMS AND METHODS FOR DETECTING PULSE WAVE VELOCITY,the complete disclosure of which is incorporated herein by reference.Another suitable oxygenation sensor is disclosed in commonly assignedU.S. patent application Ser. No. 15/200,818 filed Jul. 1, 2016, byinventors Marko Kostic et al. and entitled SYSTEMS AND METHODS FORSTROKE DETECTION, the complete disclosure of which is also incorporatedherein by reference. Still other types of tissue oxygenation sensors mayalso be used. Further, in some embodiments, multiple tissue oxygenationsensors are included in the sensor layer.

Any of thermal pads 24, 124, 224, 324, 424, and/or 524 may also bemodified to be shaped the same as, or similar to, the shape of thermalpad 624. That is, any of the bodies 80 of pads 24, 124, 224, 324, 424,and/or 524 may be modified to include a central region with a pair ofwings, such as the central region 517 and wings 518 of thermal pad 524.Fasteners may also be added in order secure the thermal pad in contactwith the patient's body.

Still other additional alterations and changes beyond those alreadymentioned herein can be made to the above-described embodiments. Thisdisclosure is presented for illustrative purposes and should not beinterpreted as an exhaustive description of all embodiments or to limitthe scope of the claims to the specific elements illustrated ordescribed in connection with these embodiments. For example, and withoutlimitation, any individual element(s) of the described embodiments maybe replaced by alternative elements that provide substantially similarfunctionality or otherwise provide adequate operation. This includes,for example, presently known alternative elements, such as those thatmight be currently known to one skilled in the art, and alternativeelements that may be developed in the future, such as those that oneskilled in the art might, upon development, recognize as an alternative.Any reference to claim elements in the singular, for example, using thearticles “a,” “an,” “the” or “said,” is not to be construed as limitingthe element to the singular.

What is claimed is:
 1. A thermal pad adapted to be placed in physicalcontact with a patient and to receive temperature controlled fluid forcontrolling a temperature of the patient, the thermal pad comprising: afirst sheet adapted to face toward the patient; a second sheet adaptedto face away from the patient; a peripheral seal coupling a periphery ofthe first sheet to a periphery of the second sheet to thereby define afluid chamber between the first and second sheets; a fluid inlet intothe fluid chamber; a fluid outlet out of the fluid chamber; and a filtersheet having a first surface facing toward the first sheet and a secondsurface facing toward the second sheet, the filter sheet positionedwithin the fluid chamber such that fluid entering the fluid inlet mustpass through the filter sheet before exiting out of the fluid outlet. 2.The thermal pad of claim 1 wherein the filter sheet, the first sheet,and the second sheet are all substantially parallel to each other; andwherein the filter sheet, the first sheet, and the second sheet all havea surface area of substantially equal size.
 3. The thermal pad of claim1 further comprising a plurality of bonds, each of the bonds couplingthe first sheet, second sheet and filter sheet together; and wherein thefirst sheet and the second sheet each have a surface area ofsubstantially equal size and the filter sheet has a surface area lessthan the surface area of the first and second sheets.
 4. The thermal padof claim 1 wherein the filter sheet includes antimicrobial substancesembedded therein, the antimicrobial substances adapted to come intocontact with and kill microbes filtered by the filter sheet.
 5. Thethermal pad of claim 1 wherein the filter sheet is adapted to filterparticles having a size of 0.2 microns or larger; and wherein thethermal pad further comprises a second filter sheet adapted to filterparticles larger than 0.2 microns and to allow particles of 0.2 micronsto pass there through.
 6. The thermal pad of claim 1 wherein the firstsurface of the filter sheet is secured to the first sheet at a firstplurality of locations and the second surface of the filter sheet issecured to the second sheet at a second plurality of locations differentfrom the first plurality of locations; and wherein the thermal padfurther comprises a non-woven sheet positioned adjacent the first sheetand adapted to come into contact with the patient, wherein both thenon-woven sheet and the first sheet are embedded with antimicrobialsubstances.
 7. A thermal pad adapted to be placed in physical contactwith a patient and to receive temperature controlled fluid forcontrolling a temperature of the patient, the thermal pad comprising: afirst sheet adapted to face toward the patient; a second sheet adaptedto face away from the patient; a peripheral seal coupling a periphery ofthe first sheet to a periphery of the second sheet to thereby define afluid chamber between the first and second sheets; a fluid inlet intothe fluid chamber; a fluid outlet out of the fluid chamber; a pluralityof bonds, each of the bonds coupling the first sheet and second sheettogether; and a filter secured to the first sheet and the second sheet,the filter positioned within the fluid chamber such that fluid enteringthe fluid inlet must pass through the filter before exiting out of thefluid outlet.
 8. The thermal pad of claim 7 wherein the filter isadapted to filter particles having a size of 0.2 microns or larger; andwherein the thermal pad further comprises a second filter and a thirdfilter, the second filter positioned upstream of the filter and adaptedto filter particles having a size of more than 0.2 microns and to allowparticles of 0.2 microns to pass there through, and the third filterpositioned downstream of the filter and adapted to filter particleshaving a size of more than 0.2 microns and to allow particles of 0.2microns to pass there through.
 9. The thermal pad of claim 7 wherein thefilter defines a fluid channel that extends into the thermal pad; andwherein the filter is made of a material that stretches in response to afirst threshold pressure of the fluid, the first threshold pressurebeing less than a second threshold pressure required to cause the firstand second sheets to stretch.
 10. The thermal pad of claim 7 wherein thefilter is a bag shaped filter having an interior that defines a fluidchannel that extends into the thermal pad; and wherein the bag shapedfilter includes a top filter sheet and a bottom filter sheet and theplurality of bonds also bond the top filter sheet and the bottom filtersheet to each other and to the first sheet and second sheet.
 11. Thethermal pad of claim 7 wherein the filter includes antimicrobialsubstances embedded therein, the antimicrobial substances adapted tocome into contact with and kill microbes filtered by the filter.
 12. Thethermal pad of claim 7 wherein the filter comprises a filter sheetcomprising a first surface facing toward the first sheet and a secondsurface facing toward the second sheet, and wherein the filter sheet,second sheet, and first sheet are all substantially parallel to eachother.
 13. The thermal pad of claim 7 wherein the first sheet isconstructed of a material having antimicrobial substances embeddedtherein, and wherein the thermal pad further comprises a non-woven sheetpositioned adjacent the first sheet and adapted to come into contactwith the patient, wherein the non-woven sheet is also embedded withantimicrobial substances.
 14. A thermal pad adapted to be placed inphysical contact with a patient and to receive temperature controlledfluid for controlling a temperature of the patient, the thermal padcomprising: a first sheet adapted to face toward the patient; a secondsheet adapted to face away from the patient; a peripheral seal couplinga periphery of the first sheet to a periphery of the second sheet tothereby define a fluid chamber between the first and second sheets; afluid inlet into the fluid chamber; a fluid outlet out of the fluidchamber; a first filter positioned in fluid communication with the fluidchamber; a second filter positioned in fluid communication with thefluid chamber; and a third filter positioned in fluid communication withthe fluid chamber and between the first filter and the second filtersuch that fluid flowing through the first filter must pass through thethird filter before reaching the second filter; wherein the first andsecond filters have a common pore rating for filtering particles of afirst size, and the third filter has a pore rating for filteringparticles of a second size, the second size being smaller than the firstsize.
 15. The thermal pad of claim 14 wherein the third filter has apore rating for filtering particles having a size of 0.2 microns orlarger and the first and second filters have a pore rating for allowingparticles having a size of greater than 0.2 microns to passtherethrough.
 16. The thermal pad of claim 14 wherein the first sheet isconstructed of a material having antimicrobial substances embeddedtherein.
 17. The thermal pad of claim 16 further comprising a non-wovensheet positioned adjacent the first sheet and adapted to come intocontact with the patient, wherein the non-woven sheet is also embeddedwith antimicrobial substances.
 18. The thermal pad of claim 14 whereinthe third filter comprises a filter sheet comprising a first surfacefacing toward the first sheet and a second surface facing toward thesecond sheet, and wherein the filter sheet, second sheet, and firstsheet are all substantially parallel to each other.
 19. The thermal padof claim 14 wherein the first filter and the second filter define firstand second channels that extend a distance into the thermal pad.
 20. Thethermal pad of claim 19 wherein the first filter and second filter areeach bag shaped and an interior of the first bag shaped filter and aninterior of the second bag shaped filter define the first and secondchannels, respectively.